Introduction:This appeal challenges an interim injunction granted by a single judge of the Delhi High Court, which restrained the appellant, Zydus Lifesciences Limited, from manufacturing or marketing its anti-cancer drug ZRC 3276 on the grounds of alleged infringement of the respondent's patent for a monoclonal antibody used in cancer treatment.
The judgment, delivered by a division bench, delves into fundamental questions about the enforcement of patent rights in the pharmaceutical sector, especially when the product in question is a life-saving medication essential for treating various carcinomas. It underscores the tension between protecting innovative intellectual property and ensuring affordable access to critical healthcare solutions, highlighting how courts must navigate the classical principles of injunctions—prima facie case, balance of convenience, and irreparable loss—while incorporating public interest as a paramount factor, as emphasized by Supreme Court precedents.
This decision not only critiques the procedural and substantive flaws in the impugned order but also sets a nuanced precedent for handling quia timet actions in patent disputes, where anticipated infringement is alleged without the availability of the defendant's product for direct comparison.
By modifying the injunction to allow market release subject to accounting safeguards, the court strikes a balance that prioritizes patient access without undermining patentee rights, reflecting broader policy concerns in a country where healthcare affordability is a pressing issue. The analytical depth of the judgment lies in its scrutiny of scientific claims, such as antibody binding specificity and amino acid sequencing, against legal standards, revealing how technical interpretations can sway outcomes in high-stakes litigation involving biologics and biosimilars.
Factual Background:The dispute revolves around competing pharmaceutical products designed to combat cancer through immune system modulation, specifically targeting the Programmed Death-1 (PD-1) protein pathway. The respondent, E.R. Squibb and Sons, LLC (a subsidiary of Bristol-Myers Squibb), holds a patent for an isolated monoclonal antibody, commercially known as 5C4, which is structurally identical to Nivolumab, a blockbuster anti-cancer drug marketed under the brand Opdivo.
This antibody is engineered to bind specifically to human PD-1, a protein in the CD28 family found on T-cells, thereby blocking its interaction with ligands PD-L1 and PD-L2 on cancer cells. This blockade prevents the deactivation of T-cells, enabling the immune system to recognize and attack malignant cells, making it effective against a wide array of life-threatening carcinomas.
The patent claims are defined by two key indicia: the antibody's specific binding to PD-1 and its composition of heavy and light chains with precise amino acid sequences. Proteins like antibodies are composed of amino acids arranged in unique sequences, and the respondent's invention emphasizes this specificity to distinguish it from non-selective bindings.
On the other side, the appellant, Zydus Lifesciences Limited, developed ZRC 3276 as a purported biosimilar to Nivolumab, claiming it offers a 70% cost reduction compared to the respondent's product, thereby enhancing accessibility for cancer patients in India. However, testing revealed that ZRC 3276 binds not only to PD-1 but also to other proteins in the CD28 family, with a statistically significant 'p' value of around 0.0001, indicating cross-reactivity.
The respondent argued that this still falls within the patent's scope, while the appellant contended that such binding violates the "specificity" requirement. Additionally, the appellant had sought regulatory exemptions by positioning ZRC 3276 as a biosimilar to Nivolumab, implying structural similarity, but without direct evidence of identical amino acid sequences.
The scientific backdrop involves immunology basics: white blood cells include lymphocytes like B-cells, which produce Y-shaped antibodies with complementarity-determining regions (CDRs) for antigen binding, and T-cells, which use PD-1 to distinguish normal from abnormal cells.
Cancer cells exploit this by expressing PD-L1, deceiving T-cells into tolerance, which monoclonal antibodies like 5C4 counteract. The factual peculiarity here is the absence of the appellant's product in the market, leading to a quia timet suit based on anticipated infringement, with no physical sample for direct mapping, forcing reliance on collateral evidence like regulatory filings and pre-grant patent responses.
Procedural Background:The proceedings originated from a patent infringement suit filed by the respondent against the appellant in the Delhi High Court, styled as a quia timet action to preempt future infringement, given that ZRC 3276 was not yet commercially available but was in advanced stages of development and regulatory approval.
The respondent sought an interim injunction under Order XXXIX Rules 1 and 2 of the Code of Civil Procedure, 1908, alleging that the appellant's product would infringe their patent by replicating the claimed monoclonal antibody. The single judge, after hearing arguments, granted the injunction in an order that restrained the appellant from manufacturing, selling, or releasing ZRC 3276, reasoning that prima facie infringement was established through indirect evidence despite the lack of product-to-claim mapping.
Aggrieved by this, the appellant filed an appeal under Section 13 of the Commercial Courts Act, 2015, registered as FAO(OS) (COMM) 120/2025, along with accompanying applications for stay and other reliefs. The appeal focused on challenging the single judge's interpretation of "specific binding," the validity of product-to-product comparisons, and the disregard for public health implications. No counter-claims for patent invalidity were raised at this interim stage, keeping the focus on injunction criteria.
Reasoning and Decision of Court:The division bench meticulously dissected the single judge's order, finding it flawed on multiple fronts, particularly in granting an absolute injunction without product-to-claim mapping and overlooking public interest. Central to the reasoning was the interpretation of the patent claim's requirement that the antibody "binds specifically to human PD-1."
The court noted the respondent's own pre-grant response defining "specifically" as excluding statistically significant binding to other CD28 family proteins, with a 'p' value threshold of less than 0.05. Applying this, the bench found ZRC 3276's 'p' value of 0.0001 indicated significant cross-binding, thus potentially excluding it from the claim's scope.
The single judge's view that "specifically" means not "exclusively" was rejected as inconsistent with the respondent's representations, and the impugned order's failure to address this contention was highlighted as a critical oversight. On amino acid sequencing, the bench critiqued the single judge's reliance on biosimilar status, where the appellant's regulatory exemption treated Nivolumab as the reference biologic, and 5C4 shared sequences with Nivolumab, leading to an erroneous transitive equality (if A equals B and C equals B, then A equals C).
The court clarified that biosimilars do not invariably share identical sequences, as variations can occur, and no evidence supported this as an inflexible rule. This exposed the fallacy of product-to-product mapping instead of the mandated product-to-claim approach under Rule 3(A)(ix) of the Delhi High Court Rules Governing Patent Suits, 2022, which requires mapping "to the extent possible," but not its complete waiver in quia timet actions.
The bench emphasized Section 48 of the Patents Act, 1970, granting exclusive rights only over "that" product, necessitating direct mapping for infringement findings. Collateral materials, like regulatory filings, were deemed insufficient for a prima facie case without expert evidence, raising arguable issues better suited for trial. Invoking Supreme Court rulings in Ramnik Lal Bhutta and Raunaq International, the court integrated public interest, noting the drug's life-saving nature, 70% cost savings, and the patent's imminent expiry on May 2, 2026.
Balance of convenience tilted against absolute restraint, as depriving patients for four months outweighed potential harm to the respondent, securable through accounts. The decision modified the injunction: the appellant could market ZRC 3276 but must file periodical accounts of sales to secure the respondent if they succeed at trial, thus protecting both IP rights and public health.
Point of Law Settled in the Case:This judgment settles several critical points in patent litigation, particularly for biologics in quia timet scenarios, affirming that product-to-claim mapping under Rule 3(A)(ix) of the Delhi High Court Patent Suits Rules cannot be entirely dispensed with, even in anticipatory actions; the phrase "to the extent possible" allows flexibility but demands maximum feasible effort, and collateral evidence alone may not suffice for prima facie infringement without raising triable issues.
It clarifies that patent claims must be interpreted consistently with the patentee's representations during prosecution, such as defining "specifically binds" to exclude statistically significant cross-binding based on 'p' values, preventing post-grant expansions of scope.
The decision rejects product-to-product mapping as a substitute for claim mapping, emphasizing Section 48's focus on the claimed invention over commercial embodiments. On biosimilars, it establishes that similarity for regulatory purposes does not automatically imply identical amino acid sequences for infringement, requiring direct evidence.
Crucially, it reinforces public interest as an integral factor in injunctions for life-saving drugs, per Supreme Court precedents, allowing courts to modify restraints by mandating account maintenance to balance IP protection with healthcare access, especially when patents are near expiry and affordability impacts vulnerable populations.
Case Title: Zydus Lifesciences Limited Vs E. R. Squibb and Sons, LLC & Ors.
Date of Order: 12 January 2026
Case Number: FAO(OS) (COMM) 120/2025,
Neutral Citation: 2026:DHC:178-DB
Name of Court: High Court of Delhi at New Delhi
Name of Hon'ble Judge: Mr. Justice C. Hari Shankar and Mr. Justice Om Prakash Shukla
Disclaimer: Readers are advised not to treat this as substitute for legal advise as it may contain errors in perception, interpretation, and presentation
Written By: Advocate Ajay Amitabh Suman, IP Adjutor [Patent and Trademark Attorney], High Court of Delhi
Suggested Titles:
Product-to-Claim Mapping in Patent Infringement Suit
Suggested Tags:
Patent Infringement, Quia Timet Action, Biosimilars, Monoclonal Antibodies, PD-1 Inhibitors, Public Interest in Injunctions, Product-to-Claim Mapping, Delhi High Court, Anti-Cancer Drugs, Intellectual Property Law, Pharmaceutical Patents, Nivolumab, Amino Acid Sequencing, Section 48 Patents Act, Rule 3(A)(ix) DHC Patent Rules
